Thursday, November 05, 2015

Multispectral imaging using a single bucket detector

Current multispectral imagers suffer from low photon efficiency and limited
spectrum range. These limitations are partially due to the technological
limitations from array sensors (CCD or CMOS), and also caused by separative
measurement of the entries/slices of a spatial-spectral data cube. Besides,
they are mostly expensive and bulky. To address above issues, this paper
proposes to image the 3D multispectral data with a single bucket detector in a
multiplexing way. Under the single pixel imaging scheme, we project
spatial-spectral modulated illumination onto the target scene to encode the
scene's 3D information into a 1D measurement sequence. Conventional spatial
modulation is used to resolve the scene's spatial information. To avoid
increasing requisite acquisition time for 2D to 3D extension of the latent
data, we conduct spectral modulation in a frequency-division multiplexing
manner in the speed gap between slow spatial light modulation and fast detector
response. Then the sequential reconstruction falls into a simple Fourier
decomposition and standard compressive sensing problem. A proof-of-concept
setup is built to capture the multispectral data (64 pixels $\times$ 64 pixels
$\times$ 10 wavelength bands) in the visible wavelength range (450nm-650nm)
with acquisition time being 1 minute. The imaging scheme is of high flexibility
for different spectrum ranges and resolutions. It holds great potentials for
various low light and airborne applications, and can be easily manufactured
production-volume portable multispectral imagers.